1. Basic knowledge of agitator

1. The composition of the agitator

The stirrer is a device that makes liquid and gaseous media force convection and uniformly mix.

The basic composition of agitator: impeller, mixing shaft, motor, accessories (reducer, frame, etc.).

2. Classification of agitators

The classification of agitators is mainly classified according to the shape of the impeller, such as frame agitator, anchor agitator, propeller agitator, double-layer agitator, folding blade agitator, turbine agitator, propeller agitator, open Turbine agitator, etc. In addition, there are side-entry mixers, cantilever mixers, frequency conversion mixers, etc.

Agitators with different impeller forms can meet different mixing requirements. For example, a turbine agitator is generally composed of 2 to 4 flat or curved blades installed on a horizontal disk. The ratio of the outer diameter, width and height of the blade is generally 20:5:4, and the circumferential speed is generally 3-8m/s. The turbine causes highly turbulent radial flow when rotating, which is suitable for the dispersion of gas and immiscible liquids and the liquid-liquid reaction process. The viscosity of the liquid being stirred is generally not more than 25Pa?s.

According to the physical properties of the medium, the capacity, the purpose of the mixing operation and other factors, determine the appropriate impeller form, size, speed and other parameters, so that the mixer can meet the needs of the mixing operation.

2. Design and application of agitator

3. Design and application of agitator

The use of agitator to stir the medium can accelerate the heat and mass transfer of the medium and accelerate the progress of chemical reactions. Therefore, the agitator is widely used in petrochemical equipment. There are many types of stirrers, and the types of stirring media are also very wide. According to the physical properties of the stirring media, they can be divided into liquid, solid and gas, of which liquid is the majority. Water is one of the common liquids. Its viscosity is very low and the stirring resistance is also small. The liquid mixing medium has high viscosity, such as butter, which can reach 1 000 000 cP at room temperature (viscosity, 1 cP=10-3Pa?s, the same below). Too much gas in the stirred liquid will cause foaming. Simple stirring is to mix two miscible liquids. Generally speaking, the stirring device is composed of a motor (motor), a stirring shaft, and an impeller. Sometimes it is equipped with a bracket, a reducer, etc. for convenience. When we design the agitator, the goal we pursue is the balance between the agitator process, machinery and cost. Our designers will fully consider the actual needs of the users of the agitator and the application range of the agitator, and design a cost-effective agitator, so that customers do not worry about the quality and maintenance of the agitator.

4. Basis for design of agitator

When designing an electric mixer, pay attention to the following points:

1) The basic parameters of the electric mixer, such as power, torque, etc., are determined according to the user's requirements for the degree of mixing, mixing time, material properties, equipment conditions and other basic parameters.

2) The basis for determination is the result obtained by practical experience and laboratory simulation, and appropriately amplified.

3) As the basis of the design, the electric mixer designer must master and accumulate the performance data of the commonly used mixing impeller and the performance data of its driving device to ensure that the requirements are met.

5. General design procedure of agitator and electric agitator

1) When we design the agitator, we can select a number of torques or torques at different speeds according to the existing D/DT (impeller diameter/tank diameter) value of the user's equipment, as well as the customer's requirements for mixing time and degree of mixing. Power requirements. Among them, the degree of stirring is restricted by factors such as material viscosity difference, specific gravity difference, and non-Newtonian fluid. We can give a classification method (for example: mild, moderate, severe, strong) (Note: different companies have different standards).

2) Select a reasonable installation height of the impeller and combine the equipment to estimate the approximate length of the mixing shaft.

3) Estimate reasonable motor power.

4) Refer to the existing performance of our factory, such as impeller power consumption, reducer, its output shaft, bracket, etc., and select the agitator that can meet the first three requirements.

5) According to conditions such as blade tip tangential speed, determine the appropriate speed and optimize the design. According to the determined conditions, use the computer program to check and analyze the power and strength of the shaft system.

Three, agitator group diagram

Folding leaf agitator

Frame stirrer-anchor stirrer

Side entry mixer